Progress in surface photoacoustic wave spectroscopy of thin films

We have recently reported on the use of surface photoacoustic wave spectroscopy to measure the electronic absorption spectra of thin molecular films.1 The technique relies on the detection of the surface acoustic waves (SAW) generated when the energy absorbed in thin surface films thermalizes with the substrate. Absorbances as low as 10−5 were detected, film absorption spectra were obtained, and laser-induced desorption cross sections were measured. Here we report an increase in detection sensitivity of almost 3 orders of magnitude as well as application of the technique to other film systems.